docs/libmachine/drivers/rpc/client_driver.go

package rpcdriver

import (
	"fmt"
	"net/rpc"

	"github.com/docker/machine/libmachine/drivers"
	"github.com/docker/machine/libmachine/drivers/plugin/localbinary"
	"github.com/docker/machine/libmachine/log"
	"github.com/docker/machine/libmachine/mcnflag"
	"github.com/docker/machine/libmachine/state"
)

type RpcClientDriver struct {
	Client *InternalClient
}

type RpcCall struct {
	ServiceMethod string
	Args          interface{}
	Reply         interface{}
}

type InternalClient struct {
	RpcClient *rpc.Client
	Calls     chan RpcCall
	CallErrs  chan error
}

func (ic *InternalClient) Call(serviceMethod string, args interface{}, reply interface{}) error {
	ic.Calls <- RpcCall{
		ServiceMethod: serviceMethod,
		Args:          args,
		Reply:         reply,
	}

	return <-ic.CallErrs
}

func NewInternalClient(rpcclient *rpc.Client) *InternalClient {
	return &InternalClient{
		RpcClient: rpcclient,
		Calls:     make(chan RpcCall),
		CallErrs:  make(chan error),
	}
}

func NewRpcClientDriver(rawDriverData []byte, driverName string) (*RpcClientDriver, error) {
	mcnName := ""

	p := localbinary.NewLocalBinaryPlugin(driverName)

	c := &RpcClientDriver{}

	go func() {
		if err := p.Serve(); err != nil {
			// If we can't safely load the server, best to just
			// bail.
			log.Fatal(err)
		}
	}()

	addr, err := p.Address()
	if err != nil {
		return nil, fmt.Errorf("Error attempting to get plugin server address for RPC: %s", err)
	}

	rpcclient, err := rpc.DialHTTP("tcp", addr)
	if err != nil {
		return nil, err
	}

	c.Client = NewInternalClient(rpcclient)

	go func() {
		for {
			call := <-c.Client.Calls

			log.Debugf("(%s) Got msg %+v", mcnName, call)

			if call.ServiceMethod == "RpcServerDriver.Close" {
				p.Close()
			}

			c.Client.CallErrs <- c.Client.RpcClient.Call(call.ServiceMethod, call.Args, call.Reply)

			if call.ServiceMethod == "RpcServerDriver.Close" {
				// If we're messaging the server to close,
				// we're not accepting any more RPC calls at
				// all, so return from this function
				// (subsequent "requests" to make a call by
				// sending on the Calls channel will simply
				// block and never go through)
				return
			}
		}
	}()

	var version int
	if err := c.Client.Call("RpcServerDriver.GetVersion", struct{}{}, &version); err != nil {
		return nil, err
	}
	log.Debug("Using API Version ", version)

	if err := c.SetConfigRaw(rawDriverData); err != nil {
		return nil, err
	}

	mcnName = c.GetMachineName()
	p.MachineName = mcnName

	return c, nil
}

func (c *RpcClientDriver) MarshalJSON() ([]byte, error) {
	return c.GetConfigRaw()
}

func (c *RpcClientDriver) UnmarshalJSON(data []byte) error {
	return c.SetConfigRaw(data)
}

func (c *RpcClientDriver) Close() error {
	log.Debug("Making call to close driver server")

	if err := c.Client.Call("RpcServerDriver.Close", struct{}{}, nil); err != nil {
		return err
	}

	log.Debug("Successfully made call to close driver server")

	return nil
}

// Helper method to make requests which take no arguments and return simply a
// string, e.g. "GetIP".
func (c *RpcClientDriver) rpcStringCall(method string) (string, error) {
	var info string

	if err := c.Client.Call(method, struct{}{}, &info); err != nil {
		return "", err
	}

	return info, nil
}

func (c *RpcClientDriver) GetCreateFlags() []mcnflag.Flag {
	var flags []mcnflag.Flag

	if err := c.Client.Call("RpcServerDriver.GetCreateFlags", struct{}{}, &flags); err != nil {
		log.Warnf("Error attempting call to get create flags: %s", err)
	}

	return flags
}

func (c *RpcClientDriver) SetConfigRaw(data []byte) error {
	return c.Client.Call("RpcServerDriver.SetConfigRaw", data, nil)
}

func (c *RpcClientDriver) GetConfigRaw() ([]byte, error) {
	var data []byte

	if err := c.Client.Call("RpcServerDriver.GetConfigRaw", struct{}{}, &data); err != nil {
		return nil, err
	}

	return data, nil
}

func (c *RpcClientDriver) DriverName() string {
	driverName, err := c.rpcStringCall("RpcServerDriver.DriverName")
	if err != nil {
		log.Warnf("Error attempting call to get driver name: %s", err)
	}

	return driverName
}

func (c *RpcClientDriver) SetConfigFromFlags(flags drivers.DriverOptions) error {
	return c.Client.Call("RpcServerDriver.SetConfigFromFlags", &flags, nil)
}

func (c *RpcClientDriver) GetURL() (string, error) {
	return c.rpcStringCall("RpcServerDriver.GetURL")
}

func (c *RpcClientDriver) GetMachineName() string {
	name, err := c.rpcStringCall("RpcServerDriver.GetMachineName")
	if err != nil {
		log.Warnf("Error attempting call to get machine name: %s", err)
	}

	return name
}

func (c *RpcClientDriver) GetIP() (string, error) {
	return c.rpcStringCall("RpcServerDriver.GetIP")
}

func (c *RpcClientDriver) GetSSHHostname() (string, error) {
	return c.rpcStringCall("RpcServerDriver.GetSSHHostname")
}

// TODO:  This method doesn't even make sense to have with RPC.
func (c *RpcClientDriver) GetSSHKeyPath() string {
	path, err := c.rpcStringCall("RpcServerDriver.GetSSHKeyPath")
	if err != nil {
		log.Warnf("Error attempting call to get SSH key path: %s", err)
	}

	return path
}

func (c *RpcClientDriver) GetSSHPort() (int, error) {
	var port int

	if err := c.Client.Call("RpcServerDriver.GetSSHPort", struct{}{}, &port); err != nil {
		return 0, err
	}

	return port, nil
}

func (c *RpcClientDriver) GetSSHUsername() string {
	username, err := c.rpcStringCall("RpcServerDriver.GetSSHUsername")
	if err != nil {
		log.Warnf("Error attempting call to get SSH username: %s", err)
	}

	return username
}

func (c *RpcClientDriver) GetState() (state.State, error) {
	var s state.State

	if err := c.Client.Call("RpcServerDriver.GetState", struct{}{}, &s); err != nil {
		return state.Error, err
	}

	return s, nil
}

func (c *RpcClientDriver) PreCreateCheck() error {
	return c.Client.Call("RpcServerDriver.PreCreateCheck", struct{}{}, nil)
}

func (c *RpcClientDriver) Create() error {
	return c.Client.Call("RpcServerDriver.Create", struct{}{}, nil)
}

func (c *RpcClientDriver) Remove() error {
	return c.Client.Call("RpcServerDriver.Remove", struct{}{}, nil)
}

func (c *RpcClientDriver) Start() error {
	return c.Client.Call("RpcServerDriver.Start", struct{}{}, nil)
}

func (c *RpcClientDriver) Stop() error {
	return c.Client.Call("RpcServerDriver.Stop", struct{}{}, nil)
}

func (c *RpcClientDriver) Restart() error {
	return c.Client.Call("RpcServerDriver.Restart", struct{}{}, nil)
}

func (c *RpcClientDriver) Kill() error {
	return c.Client.Call("RpcServerDriver.Kill", struct{}{}, nil)
}

func (c *RpcClientDriver) LocalArtifactPath(file string) string {
	var path string

	if err := c.Client.Call("RpcServerDriver.LocalArtifactPath", file, &path); err != nil {
		log.Warnf("Error attempting call to get LocalArtifactPath: %s", err)
	}

	return path
}

func (c *RpcClientDriver) GlobalArtifactPath() string {
	globalArtifactPath, err := c.rpcStringCall("RpcServerDriver.GlobalArtifactPath")
	if err != nil {
		log.Warnf("Error attempting call to get GlobalArtifactPath: %s", err)
	}

	return globalArtifactPath
}

func (c *RpcClientDriver) Upgrade() error {
	return c.Client.Call("RpcServerDriver.Upgrade", struct{}{}, nil)
}